USING MULTIPLE-VARIABLE INDICATOR KRIGING FOR EVALUATING SOIL QUALITY

Soil quality is the most important factor for sustaining the global bi osphere. Soil quality may be defined in several different ways includi ng productivity, sustainability, environmental quality, and effects on human nutrition. To quantify soil quality, specific soil indicators n eed to be measured spatially. These indicators are mainly soil propert ies whose values relate directly to soil quality but may also include policy, economic, or environmental considerations. Because assessing s oil quality is complex, the individual soil quality indicators need to be integrated to form a soil quality index. This integration needs to be flexible enough to evaluate soil quality at spatial scales ranging from the farm to the regional level, be applicable to all types of ag ricultural land use, and be able to incorporate all types of soil qual ity information. We have developed a multiple-variable indicator rangi ng (MVIK) procedure that may provide a means to integrate soil quality parameters into an index to produce soil quality maps on a landscape basis. These maps would indicate the areas on a landscape that have a high probability of having good soil quality according to predetermine d criteria. This procedure can provide probability maps based on any r ange of chosen criteria and thus is universally applicable. In additio n, it allows the identification of the indicator parameter(s) responsi ble for zones of low soil quality, thus allowing specific management p lans or land use policies to be developed.